1. Field of the Invention
The present invention relates to a bus arbitration technique which is the most important part of the conventional cell bus forming technique in which data transmissions are carried out with packets of a certain size. Unlike the conventional bus, the cell bus generally contains the addresses of the transmitter and receiver within the packets, and therefore, a high speed data transmission is possible at 1 to 1 or 1 to N (where N is the number of arbitrary groups or all nodes). Therefore, this technique is applied to multi media ATM terminals, ATM concentrators, and small scale ATM switching systems.
The present invention relates to a self-control type bus arbitration circuit and an arbitration method, in which the bus arbiter of the conventional technique is not required. More specifically, the present invention relates to a self-control type bus arbitration circuit and an arbitration method, in which bus modules (to be called "entities" below) for transmitting the data through parallelly connected buses arbitrate the buses for themselves by utilizing a proper common information, so as to control the access priority of the buses.
2. Description of the Prior Art
In the conventional technique, a plurality of entities which are connected to cell buses first request for a bus ownership to a bus arbiter. The bus arbiter grants the right of use of bus to a particular entity based on a procedure or method. The granted entity uses the bus, and then negates the bus request, while the bus arbiter recovers the bus ownership. Therefore, in the conventional technique, additional signal lines for requesting for a bus use are needed, and the number of entities which can request for bus use is inevitably limited to the number of the signal lines.
For example, in the case where 32-bit data bits are used as the bus request signal, only 32 entities can be connected to the same bus, and a discriminating information for recognizing a bus request cycle is separately needed. Further, the buses are connected to the entities which are assigned with different priorities, and therefore, the priorities have to be arbitrated. Therefore, not only signal lines for requesting for bus uses are needed, but also the priorities of the entities have to be transmitted to the bus arbiter.
That is, the information such as video and audio information which is sensitive to the time delay should be granted a minimum time delay, while the entities which processes less time-sensitive data should be granted lower priorities. Further, in the case where a bus arbiter is separately present, a separate procedure or method for granting the bus ownership has to be necessarily provided.